<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
</head>
<body>
<a style="position: fixed;right: 30px;bottom: 30px;" href="#top">返回顶部</a>
<div id="top" style="height: 2000px;background-color: #ddd;">
    <div style="position: relative;background-color: beige;width: 300px;margin: 0 auto;height: 300px;">
        <h1>数据</h1>
        <a style="position: absolute;right: 0;bottom: 0;">aaaaaa</a>
    </div>
</div>

</body>
</html>